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Discussion Starter · #1 · (Edited)
Hi all,
I've been having some low idle issues with my 2002 4wd 2.0l 2dr tracker Canada model for about a year now. No check engine light. It hasn't driven very far in a year due to a possibly related no start and rusted gas tank issue which I believe I have fixed.

My Vitara always takes a bit of depression on the gas to get it to start. It will run until up to temperature and then will keep stalling. I am well aware of the CPS getting hot in these vehicles, and I have tried putting a cold damp rag on the cps when it gets to full temperature, which does not help this issue. I am 90% sure this is not related to the common CPS overheat problem.

As of today I have been taking a second look into the IAC operation. After cleaning the soot out of the housing area, I checked resistances between the pins as per the manual and they were all good. I then went to check the plunger operation, and since I work alone took a video of the plunger operating. The plunger appeared to be surging as my vitara was struggling to start but does operate as per manual intended (moves when the key is switched between the ON and OFF position).

Lastly, when my vitara gets up to temperature and stalls, if I unplug the IAC connector it will start up again and run, but will idle high and unsteadily. If I add a cold rag to the CPS, there is no change and it will still not start until cooling off. This leads me to believe the IAC is acting up.

I have uploaded and attached the video below, if anyone can tell me if the IAC should be surging the way it is. If any additional information is needed I'd be glad to provide.

 

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I don't know you can test the IAC removed from the throttle body - it's a stepper motor type IAC and once the ECU can move it, as can clearly be seen, then I'd say it's working..
 

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99 Tracker, 5 door, 2L, 4x4
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Have you connected a scanner and monitored the ECT ??
 

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Discussion Starter · #4 ·
Have you connected a scanner and monitored the ECT ??
I did connect my scanner but I do not see anything abnormal regarding the ECT.

I pursued more testing today with regards to disconnecting the IAC at running temperature. With the IAC plugged in the vitara will start again after stalling, but I must keep pressing the gas pedal or it will drop in rpm and stall. With the IAC unplugged the rpm is high at start 1500 or so but does fall back to under 1000. It will not stall with the IAC unplugged.

In both scenarios the vitara is running far too rich on the short term fuel trim (between -20 and -25). At times the trim does go back to 0, but keeps running rich, making the trim go back into the -20's.

I have recently replaced both the upstream and downstream oxygen sensors when replacing the catalytic converter. Both read 0.9 to 1.1 and appear to be working. When the rpm drops I will see B1S1 upstream oxygen sensor drop to about 0.2 - 0.4 while B1S2 will remain near 0.9

The ECU was swapped (I own two working ones) when I was pursuing the no start issues around 6-8 months ago. Since then I have not yet been able to get the vitara onto the highway for around a year, and such the ECU calibration hasn't been done. The vehicle only stalls when letting off the gas in idle or slow traffic, so I figured if I can get it there with the IAC unplugged I could possibly get the ECU to calibrate the fuel mixture as per the driving cycles in the manual. Before starting the calibration I would plug the IAC back in, and I would hope the vehicle fixes the fuel mixture itself based on the driving cycles. I'm not concerned about needing a tow back home, I'm just not sure if this is a waste of my time. If it has possibility to fix the problem I will try it.
 

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The B1S1 should be actively switching without bias between .1 and .9, when the ECU is in closed status..

Can you record this in graph mode and post.. ??
 

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I believe the IAC is functional, there is an issue with fuel control, at idle what is the MAF reporting ??
 

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Discussion Starter · #7 ·
My cheaper scanner (no graphing) shows B1S1 sometimes drops to 0.4 when I let my foot of the gas allowing it to stall. My bluetooth scanner which has graphing shows that both oxygen sensors maintain between 0.9 and 1.1 at all times. I took a picture of the graph at time it stalled. I tried a few times but the resulting graphs are similar.
Screenshot_20200703-182416_Torque.jpg
 

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You definitely have an issue with the Fuel control, both the O2 are reporting full rich, this will destroy the CAT if you run it like this... The fact that it reports .4 on fuel cut (decel) confirms control..

The first item I would check is the FI, do you have a fuel pressure gauge ??
 

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Discussion Starter · #9 ·
I do believe the last cat got destroyed from being too rich (hence why I just put a new one in couple months ago).

I couldn't find the right fitting adapter in my local area for connecting a pressure gauge to the fuel rail, so I ordered one and should arrive within one week. So as of this time I don't have a fuel pressure gauge but hopefully I will soon.

I'm not sure if whether it is getting to much fuel or rather not enough air. I cleaned around the throttle body and intake the best I can without taking them off, but they did have a fair amount of carbon build up. It is possible that airflow is being restricted somewhere.
 

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If you have a gauge, the easiest route would be to remove the plug from the fuel rail, drill, tap and install a fuel rated schrader valve.
 

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If it was an air restriction you would not be able to start it... again what does the MAF report in G/sec (graph mode)..

Where are you located ?
 

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Try this quick test,, idle engine and monitor the B1S1, one at a time unplug the fuel injectors, if you have a stuck FI that one will not drop the reading..or stumble the engine....
 

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Another direction, when you fuel the vehicle do you top it off ??

When was the last time you filled up ??
 

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Discussion Starter · #14 ·
Fuel pressure Gauge was expensive locally too so I'm waiting for that in the mail as well. I'm located in Prince Edward Island.

I must have overlooked your reply about the MAF. I attached the graph in the photo. The MAF reads around average 35G/s when I am maintaining 1000 rpm using the gas pedal. After that showed in graph is when I let my foot off the gas for it to idle and it stalls. The last part where MAF ranges at about 14G/s I was cranking the engine and it was sputtering, but won't start until I press the gas.

The problem is that to check the MAF at idle I must take my foot off the gas and it will stall instantly.
 

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Discussion Starter · #15 ·
Vehicle was previously only filled half way since the prior gas tank had holes at the seams. I have since replaced the gas tank. It is currently under half full, and I have to drop the gas tank tomorrow to check the fuel gauge wires (fuel gauge working intermittently). Thus when I remove the gas tank tomorrow I will drain it again and replace with fresh gas.

Edit: last time I filled with gas was maybe 2 or 3 months ago, but at the same time I put in stabilizer since I knew I was still having issues and it would not be driven much.
 

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With regards the fuel tank, was interested if there was a flooded charcoal canister issue,, but you have negated that, thanks..

Re: location, sorry I am way across the mother land, so unable to assist with personal..

Not likely an intake resistance based on MAF..
 

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Althogh you do not show an air flow restriction, consider..

Here are some of the most common symptoms of a faulty mass airflow sensor:
  • The engine is very hard to start or turn over.
  • The engine stalls shortly after starting.
  • The engine hesitates or drags while under load or idle.
  • Hesitation and jerking during acceleration.
  • The engine hiccups.
  • Excessively rich or lean idling.
Try running the engine with MAF disconnected, will run on predetermined matrix..
 

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Discussion Starter · #18 ·
I tried the FI test and none seem stuck since at each one unplugged the engine would start hesitating more.

Unplugging the MAF allows the vehicle to start without depressing the gas pedal, but it only runs for between 3-10 seconds each time and around 750-820 rpm.
 

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Discussion Starter · #19 ·
I'm going to have to wrap up for this evening, I did get some interesting results with the MAF unplugged (actually ran quite well until it randomly cuts out without hesitation) the short term fuel trim was hovering between around -5% and +5%. I'll try to get them graphed and post them back here tomorrow.
 

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I'm going to have to wrap up for this evening, I did get some interesting results with the MAF unplugged (actually ran quite well until it randomly cuts out without hesitation) the short term fuel trim was hovering between around -5% and +5%. I'll try to get them graphed and post them back here tomorrow.
That is a good indication the the MAF is N/S... Have a good night...
 
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